Hydrocarbon injector for blastfurnaces



Feb. 5,2.1963 J. CORDIER HYDRocARBoN INJEcToR Foa BLAsT-FURNAcEs lFiledNOV. 24, 1961 INVENTOR JEAN CORDIER United States Patent O It is knownthat techniques of injection of hydrocarbons in blast-furnaces have beenstudied, and are now applied commercially. It is also known that inorder to carry out such injections, it is preferable to atomize liquidfuels by means of a compressed gas which is hydrocarbon or not and withwhich the liquid has been mixed, by expansion of the mixture through anorifice in which the ilow takes place at sonic speed.

There do exist a few known 'types of injectors which inject liquid orgaseous hydracorbons into blast-furnaces and which make use of thisprinciple. To a varying extent, they all have the disadvantage ofbecoming obstructed after a certain time of operation by thecarboncharged deposits derived from a decomposition vof hydrocarbonswhich is usually referred-to as cracking or coking This decomposition ofhydrocarbons which is productive of carbon-charged deposits is assistedby the heating of the nose of the injector, and by any geometric factorwhich is conducive to the formation of hydrocarbon droplets which eithersettle on or run on the nose of the injector. This phenomenon, which isalready highly troublesome if only one kind of hydrocarbon which iseither liquid or gaseous is injected, is accordingly even furtheraccentuated if a liquid hydrocarbon and a gaseous hydrocarbon areinjected simultaneously, above all if one of these latter contains insuspension pulverized coal.

Furthermore, the complete injector unit which is usually composed of anumber of concentric tubes often has a considerable length. Since thedilierent tubes are subjected to temperatures which can be variable andwhich are subject to differences between each other which are bothsubstantial and variable, the expansions can result in prohibitiverelative displacements of the different tubes, thereby producingirregular atomization which assists the formation of carbon-chargeddrops and deposits.

The object of the present invention is to overcome these drawbacks andto produce an injector which makes it possible to employ simultaneouslya liquid hydrocarbon fuel and an atomizing gas, hydrocarbon or not,while one of the two or both can hold in suspension pulverized coal,without any troublesome deposit of a product which is charged withcarbon and which is derived from a decomposition of fuel being liable totake place at the nose of the injector.

With this object in view the hydrocarbon injector for blast-furnaces ofthe present invention comprises an outer heat resisting tube, anintermediate tube co-axial therewith for the supply of atomizing gas, aheat resisting cylindro-conical head terminating said intermediate tubeand having an outlet orifice the length thereof being substantiallyequal to its diameter, a central coaxial tube for "ice the supply of atleast a liquid hydrocarbon fuel, a cylindrical head terminating saidcentral tube and having a central passage for the flow of fuel adaptedto slide freely into the cylindro-conical head, the outlet extremity ofthe cylindrical head being at a distance from said outlet oritice of thecylindre-conical head comprised between twice and eight times thediameter of said outlet orifice, said cylindrical head being providedwith peripheral passages for the iiow of the atomizing gas having atotal section such that the velocity of said gas is comprised between 50and l5() metres per second, bearing means between said cylindre-conicalhead and said cylindrical head, and a spring to apply said cylindricalhead against said cylindro-conical head.

The bearing means between the cylindro-conical head and the cylindricalhead are preferably constituted by a conical bearing surface formedinside the cylindroconical head and ns iixed to the cylindrical head andadapted to bear against the conical bearing surface. The peripheralpassages provided in the said cylindrical head which terminates thecentral tube may be constituted by helical grooves which impart avortical movement to the atomizing gas so as to pull away any drops ofliquid which can possibly be formed.

As will be understood, thepresent invention provides a more reliablemethod of maintaining the good geometry of the injector, Which governsthe perfect atomization of the fuel. A strictly accurate centering ofthe inner tube through which the liquid hydrocarbon fuel is supplied andwith respect to the nose of the injector proper is thus maintained inspite of variations of temperature and of pressure to which the deviceis subjected in the course of its operation. Since it is cooled by thecircula-tion of the liquid fuel, the inner tube is thus always at alower ternperature than that of the intermediate tube through which theatomizing gas is supplied at a relatively low rate of flow.

Since the injector unit as a whole vis frequently greater in length thantwo metres, the expansions could result in `substantial relativedisplacements of the extremity of the inner tube with respect to thenose of the injector, which would seriously disturb the atomizingprocess. This drawback is completely eliminated if the heads which formthe ends of the two inner tubes are so arranged as -to bear against eachother, and if they are held in contact in their most effective relativeposition by means of a spring which absorbs all differences of expansionbetween the tubes.

The elements of this combination thus work together so as to preventthe'formation of any carbon-charged deposit by virtue of a practicallycomplete entrainment of the drop-s which are liable to form at the noseof the central tube of the injector, and by virtue of the maintenance ofa relatively low temperature in the region in which the atomizationtakes place.

Other objects and advantages of the invention will be apparent duringthe course of the following description, reference being made to theaccompanying drawing, wherein:

FIG l is an -axial cross section of the fluid supply portion B of theinjector of the present invention; and

FIG. 2 is an axial cross section of the injection portion A of theinjector of the present invention.

In these figures, there have been drawn to the same scale the twoextremities of the injector which have been disposed one above the otheron account of the dimensional requirements of the drawing, but it isquite clear that these two portions are each in the line of extension ofthe other. The portion A is the injection extremity which finds accessinto the tuyere of the blast-furnace, whilst portion B is the rearportion through which the supply of fluids is effected. The total lengthof an injector can reach two to three metres according to the dimensionsof the blast-furnace considered, and the central portion thereof whichis composed only `of concentric tubes has been omitted from thedrawings.

The injector first comprises an intermediate tube 1 of heat-resistingsteel terminating in a frusto-conical head 2 also of heat-resistingsteel and forming an angle of 30 with the axis of the tube 1, any anglesmaller than 35 being particularly conducive to the reflection of theradiations produced by the blast-furnace into which the injector isintroduced, and consequently conducive to heat insulation. In thisexample, the head 2 is made of solid heat-resisting steel, theinsulating qualities of which are less favorable than those offered byan insulating refractory material, but which has better behavior inservice. The head 2 comprises `an axial outlet orifice 3, the length ofwhich is approximately equal to the diameter thereof and which isslightly flared at the outlet end so as to facilitate the divergence ofthe jet of fuel, as will be stated below.

The injector also comprises a central tube y4 which serves for thesupply of liquid fuel and which terminates in a head 5 fitted with aterminal passage 6 which is coupled to the tube 4 through theintermediary of a convergent nozzle 7.

An outer tube 12 of heat-resisting steel protects the whole injectorunit against heating by radiation and `by convection. A circulation ofcooling 'air can additionally be provided between the tubes 1 and 12.The air then passes out through the holes 13.

The strictly accurate centering of the tube 4 and of the orifice 6 withrespect to the tube 1 and the head 2 is ensured by means of helicoidalgrooves 14 machined in the head S and which play the part of spacingelements by sliding with moderate play inside a bore 15 of the head 2.The said helicoidal grooves 14 permit the flow of atomization air whicharrives through the space between the tubes 1 and 4 and impart to thesaid flow of air a very rapid movement of rotation which is maintainedwithin the mixing chamber and in the orifice 3.

Moreover, a -substantial expansion of the atomizing gas takes placeinside the said helicoidal grooves and this expansion, in conjunctionwith the gyratory movement imparted to the gas, produces an excellentatomization of the liquid which passes out of the passage 6. rhe conefrustum 16 which terminates the head 5 plays the part of a drop-remover.-If a drop tends to form at this point, it is immediately dispersed bythe vortical current which encloses the jet of liquid, and can neithersettle on the walls nor form a carbon deposit. The vortical current andthe flared and rounded shape of the orifice 3 produce a substantialdivergence of the atomized jet of fuel, thereby resulting in rapidmixing with the blast of the furnace and in a rapid and completecombustion.

It is naturally immaterial, within the spirit of the present invention,whether the -helical grooves 14 are formed on the head 5 or on the head2. In the present example, they are formed on the outer surface of thehead 5, but they could be formed on the inner surface of the head 2,these two solutions being equivalent. In the second case, the outersurface of the head 5 would be smooth. The important feature is that thetwo heads are capable of sliding freely one inside the other, and thatpassages for the flow of the atomizing gas having a suitable section aredisposed between the said two heads. This feature must be taken intoconsideration for the interpretation of the claims which appear at theend of the present application.

In normal service, the inner tube 4 is powerfully cooled by thecirculation of a liquid fuel whilst the tube 1 is cooled to aconsiderably lesser extent by the low-velocity circulation of theatomization air. It follows as a result that substantial and variabledifferences of temperature between these two tubes can arise. In orderto prevent the expansions from producing a relative displacement of theheads 2 and 5, which would result in faulty atomization in certainpositions, the tubes 1 and 4 can be adapted to slide freely one withrespect to the other, .and the heads 2 and 5 are maintained in contactby means of a powerful spring 17. To this end, the head 2 is providedwith a conical bearing surface 1S, and the head 5 is provided with tins19 which are brought to bear .against the said bearing surface 18 whilenevertheless permitting the atomization air to circulate between thesaid tins. The spring 17 is appiied on the one hand against a shoulderedportion 29 which forms one piece with the inner tube 4 and on the otherhand against a threaded cap 21 which is rigidly fixed to the tube 1.

The supply of fuel is carried out by means of a tube 22, the atomizationair is introduced through a junction 23, while the additional coolingair can be introduced round the tube lt through a junction 24.Fluid-tightness between the two sliding tubes 1, 4 is ensured by meansof conventional toric sealing-rings 25a, 2Sb.

The tube i2 need not necessarily be of heat-resisting steel over itsfull length. The said tube is extended in that portion thereof which isnot exposed to the radiation of the blast-furnace charge by a tube 12aof ordinary steel.

The said injector can operate, for example, under the followingconditions. The central tube 4 which terminates in a passage 6 having adiameter of 1.7 mm. is supplied with fuel oil at a pressure of 7kilograms per square centimetre with an hourly rate of ow of kilogramsper hour. The orifice 6 is placed at a distance of 1,2 mm. from theoutlet section of the orice 3, the minimum diameter of the said orificebeing equal to 4 mm. The gas blown round the central tube is air, at apressure of 4 kilograms per square centimetre with an hourly rate of owof 18.5 kilograms per hour, namely approximately 14.3 Nm per hour.

The injector is fixed to the blast-furnace by means of any desiredsystem of fixation constituted for example by a tube 26 inside whichslides the tube 12a, the injector being held in position by means of athreaded cap 27 which makes it possible for the injector to be easilydismantled.

It is obvious that variations and modifications may be resorted to bythose skilled in the art without departing from the scope of theinvention as disclosed in the present specification and defined by theappended claims.

What s claimed as new and desired to be secured by Letters Patent is:

1. A hydrocarbon injector for blast furnaces= which comprises an outerheat resisting tube, an intermediate tube co-axial therewith for thesupply of atomizing gas, a heat resisting cylindro-conical headterminating said intermediate tube and having an outlet oritice thelength thereof being substantially equal to its diameter, a centralcoaxial tube for the supply of at least a liquid hydrocarbon fuel, acylindrical head terminating said central tube and having a centralpassage for the flow of fuel adapted to slide freely into thecylindro-conical head, the outlet extremity of the cylindrical headbeing vat a distance from said outlet orilice of the cylindro-conicalhead comprised between twice and eight times the diameter of said outletorifice, said cylindrical head being provided with peripheral passagesfor the flow of the atomizing gas having a total section such that thevelocity of said gas is comprised between 50 and 150 metres per second,bearing means between said cylindre-conical head and said cylindricalhead, and a spring to apply said cylindrical head against saidcylindro-conical head.

2. The combination of claim 1 wherein said bearing References Cited inthe le of this patent means are constituted by a conical bearing surfaceformed UNITED STATES PATENTS inside the cylindre-conical head and finsxed to the 758,206 Grundeu et al APL 26, 190,4 cylindrical head andadapted to bear against the conical 1,189,992 Nicholson July 4 1915bearing surface. 5 1,813,083 Pyanhow July 7, 1931 3. The combination ofclaim 1 wherein said peripheral 2,372,283 Kooistra Mar. 27, 1945passages of the cylindrical head are constituted by helical FOREIGNPATENTS grooves' 47,572 Denmark July 24, 1933

1. A HYDROCARBON INJECTOR FOR BLAST FURNACES, WHICH COMPRISES AN OUTERHEAT RESISTING TUBE, AN INTERMEDIATE TUBE CO-AXIAL THEREWITH FOR THESUPPLY OF ATOMIZING GAS, A HEAT RESISTING CYLINDRO-CONICAL HEADTERMINATING SAID INTERMEDIATE TUBE AND HAVING AN OUTLET ORIFICE THELENGTH THEREOF BEING SUBSTANTIALLY EQUAL TO ITS DIAMETER, A CENTRALCOAXIAL TUBE FOR THE SUPPLY OF AT LEAST A LIQUID HYDROCARBON FUEL, ACYLINDRICAL HEAD TERMINATING SAID CENTRAL TUBE AND HAVING A CENTRALPASSAGE FOR THE FLOW OF FUEL ADAPTED TO SLIDE FREELY INTO THECYLINDRO-CONICAL HEAD, THE OUTLET EXTREMITY OF THE CYLINDRICAL HEADBEING AT A DISTANCE FROM SAID OUTLET ORIFICE OF THE CYLINDRO-CONICALHEAD COMPRISED BETWEEN TWICE AND EIGHT TIMES THE DIAMETER OF SAID OUTLETORIFICE, SAID CYLINDRICAL HEAD BEING PROVIDED WITH PERIPHERAL PASSAGESFOR THE FLOW OF THE ATOMIZING GAS HAVING A TOTAL SECTION SUCH THAT THEVELOCITY OF SAID GAS IS COMPRISED BETWEEN 50 AND 150 METRES PER SECOND,BEARING MEANS BETWEEN SAID CYLINDRO-CONICAL HEAD AND SAID CYLINDRICALHEAD, AND A SPRING TO APPLY SAID CYLINDRICAL HEAD AGAINST SAIDCYLINDRO-CONICAL HEAD.